This invention pertains to detergent compositions having enhanced suds regulating activity over a broad range of usage and temperature conditions comprising a surface-active agent and a suds regulating system. The suds regulating system contains a liquid hydrocarbon, an adjunct material selected from solid hydrocarbons, fatty esters and mixtures thereof and a hydrophobic silica. The solid hydrocarbon adjunct material can be represented by species having a melting point in the range from about 45.degree. C. to about 60.degree. C. Preferred fatty esters can be fatty acid esters of mono- or polyhydric alcohols having from 1 to 8 carbon atoms in the alkyl chain.
The effective and uniform control of the quantity of suds formed during the laundry operation is a long-standing and well-known product formulation aspect which desires additional improvement. Excessive sudsing can affect the overall textile cleaning and fabric benefits frequently conferred by modern detergent compositions, particularly when the washing treatment is carried out in drum washing machines. Too much sudsing in the washing machine is undesirable because not only does it interfere with--diminish--the action of the laundry liquor upon the fabrics, but also residual suds in the washing machine can be carried over to the rinse cycle. This will not only increase the amount of suds in the rinse with the inherent difficulties of suppressing it but also can interfere with active-agents added to the rinsing step such as textile softeners.
As one could expect the prior art relative to detergent suds control is, commensurate with the efforts spent, very crowded and diverse. All the individual ingredients of the detergent compositions herein are well-known in the detergent art and have found application for various functions. U.S. Pat. No. 3,207,698 to Liebling et al., assigned to Nopco Chemical Company, discloses composition and method for defoaming aqueous systems wherein a hydrophobic precipitated silica having an alkaline pH is combined with a liquid hydrocarbon carrier. It is mentioned that the defoaming compositions are particularly well-suited for preventing and/or abating foam in aqueous system such as in concentrated and/or diluted black liquor systems produced during the alkaline pulping process, in latex paint systems and in acidic white water systems of the paper making process. German patent application DOS 23 35 468 discloses detergent compositions wherein a silicone/silica suds controlling agent is releasably incorporated into a water-soluble or water-dispersable, substantially non-surface-active, detergent-impermeable carrier. French Pat. No. 1.465.407 discloses detergent compositions having regulated suds wherein the regulating function is provided through the use of a hydrocarbon having a boiling point above about 90.degree. C. in conjunction with a fatty acid having from 12 to 31 carbon atoms. The hydrocarbon can be represented by a 1:1 mixture of a liquid paraffin and a waxy paraffin. The suds regulant is incorporated into the detergent composition through slurrying with the other ingredients and spray-drying the slurry so obtained in a conventional manner. French Pat. No. 1.489.395 relates to detergent compositions having controlled suds through the use of a system containing essentially a fatty acid having from 12 to 18 carbon atoms in conjunction with a waxy hydrocarbon having a melting point below 100.degree. C. The compositions according to the '395 patent are prepared by separately agglomerating the suds regulating mixture or by spraying the suds regulating agents onto the detergent base-powder. German patent application DOS 25 09 508 discloses detergent compositions capable of providing effective suds control through the combined use of a system comprising a micro-crystalline wax having a melting point of from 35.degree. C. to 125.degree. C. in combination with a suds suppressing amount of a silicone suds controlling agent releasably incorporated into a water-soluble or water-dispersable, substantially non-surface-active detergent impermeable carrier.
Notwithstanding the known shortcomings, prior art compositions could provide at premium cost acceptable suds regulating activity in commercial detergent products. However, known detergent suds regulating technology can be deficient inasmuch as it requires relatively high levels (&gt;3%) of the regulant component(s) which levels can adversely affect the physical parameters of the finished product and the ease of manufacturing. From a performance point of view, known suds regulating systems can affect performance due to a functional deficiency in one or more of the following areas: decreased regulatory activity at temperatures in the range from about 75.degree. C. up to the boil; decreased suds regulating activity in soft water; insufficient flexibility against stress conditions inclusive of low soil/high product usage and/or low water hardness; and no uniform control over the practical range of laundry temperatures extending from ambient temperature up to the boil. There is thus a standing desire for performance and additional reasons as set forth above to make available a robust suds regulating system capable of providing superior activity over the whole range of laundry conditions occurring in the treatments as, for example, carried out by housewives.
It is a main object of this invention to provide detergent compositions having effective and uniform suds control over the complete range of temperatures from ambient temperature up to the boil.
It is another object of this invention to provide detergent composition with effective and uniform suds control during the laundry operation under conditions of low water hardness.
It is still another object of this invention to provide detergent compositions having effective and uniform suds control under conditions of low soil and high product usage, possibly in presence of low hardness water.
The objectives set forth above and other advantages can now be obtained with the aid of the detergent compositions of this invention which are described in more detail hereinafter.